Final answer:
The statement in the question is false. Substances with higher lipid solubility diffuse more quickly through the lipid bilayer of cell membranes. Lipid-soluble molecules like O2 and CO2 can effortlessly pass through the membrane down their concentration gradients via passive transport.
Step-by-step explanation:
The statement 'the greater the lipid solubility of a substance, the slower the substance can diffuse through the membrane's lipid bilayer down its concentration gradient' is False.
In biology, we learn that substances with a high lipid solubility can actually diffuse more rapidly through the lipid bilayer of cell membranes, as the lipid bilayer is composed of hydrophobic (nonpolar) tails. Therefore, nonpolar or lipid-soluble substances will integrate more easily into this hydrophobic environment and diffuse across more swiftly than polar or less lipid-soluble substances. Lipid-soluble molecules such as O2 and CO2 are examples of substances that readily diffuse through the lipid bilayer down their concentration gradients without the need for energy input (passive transport).
For polar or charged substances that have low lipid solubility, such as glucose or ions, the cell employs facilitated diffusion, where specific transport proteins or channels in the membrane assist these substances in crossing the membrane.